Fluidic oscillator having a sting mounted in a resonant cavity

ABSTRACT

A resonant oscillator produces sonic oscillations from a steady fluid flow. The oscillator includes a stationary pointed sting or rod that extends outwardly from a symmetrical resonating cavity. An inward end of the cavity is closed by a diaphragm which oscillates, due to pressure variations in the cavity. The oscillating diaphragm can serve as a prime mover for mechanical mechanisms or an electrical transducer.

nited States Patent 1 Curto 1 FLUIDIC OSCILLATOR HAVING A STING MOUNTED IN A RESONANT CAVITY [75] Inventor: Paul A. Curto, Bethesda, Md.

[73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC

[22] Filed: Dec. 7, 1973 [2]] Appl. No.: 423,044

1451 Feb. 11,1975

3.555.314 1/1971 Vallardel et a1 310/15 3,686,520 8/1972 Campagnuolo 310/15 3,772,541 l1/1973 Campagnuolo et a1 310/15 3,783,310 l/1974 Campagnuolo et a1 310/15 3.798.475 3/1974 Campagnuolo et a1 137/831 X Primary Examiner-William R. Cline Attorney, Agem. or Firm-Nathan Edelberg; Robert F. Gibson; Saul Elbaum [57] ABSTRACT 12 Claims, 3 Drawing Figures nose-cams 32 [521 U.S.CI 137/826, 137/831, 310/15 [51] Int. Cl. FlSc 3/00, H02k 35/00 [58] Field of Search 137/831, 826; 310/15; 116/137 R, 137 A [56] References Cited UNITED STATES PATENTS 3,169,507 2/1965 Rich 116/137 A 3,278,165 10/1966 Gaffney 116/137 A X UTILIZATION mus 1 F LUIDIC OSCILLATOR HAVING A STING MOUNTED IN A RESONANT CAVITY RIGHTS OF THE GOVERNMENT The invention described herein may be manufactured, used, and licensed by or for the United States Government for governmental purposes without the payment to me of any royalty thereon.

CROSS-REFERENCE Cross-reference is made to my co-pending U.S. Payent Application Ser. No. 47,505, Sting Oscillator, filed June l8, 1970, which is assigned to the same assignee as this application, namely, the Government of the United States, as represented by the Secretary of the Army.

BRIEF DESCRIPTION OF THE PRIOR ART In the past, fluidic sonic oscillators have been developed by utilizing curved fluid paths that cause pressure oscillations in the fluid. A diaphragm is disposed within the oscillator structure to sense the pressure variations and produce an electrical oscillating output. Other types of fluidic oscillators require the inlet of pulsating fluids that are directed against a diaphragm which may be used as a prime mover for an electrical transducer.

Although several of the prior art approaches operate satisfactorily, they require precise manufacture which necessitates a relatively large expense. Also, due to the relative complexity of the structure of prior art fluidic sonic generators, their reliability is somewhat less than desired.

BRIEF DESCRIPTION OF THE/PRESENT INVENTION The sting oscillator is a device which converts steady state fluid movement into oscillatory fluid movement. This movement can be used to actuate a diaphragm within the structure of the oscillator. Basically, the device consists of a sting or pointed rod, placed along the axis of a symmetrical resonating cavity. The sting may be either a two or three dimensional, concentric design to match a similarly dimensioned cavity. Operational devices in two and three dimenstional modes are well known in the fluid art. However, for purposes of convenience, the present invention will be discussed in terms of a three dimensional device. The sting and cavity are then positioned axially or centrally in either a steady free flow field of fluid or in the path of a jet flow, as produced by a nozzle. Vortices shed from the sting cause the cavity to trigger into oscillation. That is, the pressure of the fluid alternately increases and decreases in the cavity with periodic response. Pressure waves are sent out in all directions at the frequency of oscillation.

The cavity may be of any transverse-cross sectional shape as long as it is radially symmetric. The sting placement in the cavity is critical to resonance characteristics. Also, the area of the cavity opening, cavity geometry, angle of sting, and the shape of the sting affect the performance. Essentially, to achieve optimal resonance, the vortex-generating frequency of the sting should be a harmonic of the cavity resonant frequency.

Since the cavity frequency is a function of temperature, the oscillation will likely be a function of temperature as well. Thus, the oscillator may be a temperature sensing device.

From a practical point of view, the advantages of the present oscillator design are many. For example, the concentric simple geometry of the oscillator makes it inexpensive to manufacture and easy to assemble. The few number of components render the structure rugged and resistant to both shock and spin. No nozzle is required for triggering although a nozzle may be used if desired. The present inventive concept permits an oscillator to be built in three dimensional conical form or two dimensional wedge flow form. The oscillator can operate at high flight velocities thus rendering it appropriate for use in missles. The inventive design allows the oscillator to generate relatively loud noise and pres sure waves very efficiently in those applications where these functions are important. The present sting oscillator can be adapted for use as a fuze for an armed missle.

The oscillator can operate in different fluid mediums such as air, water, or in the presence of other gases and fluids. The diaphragm of the invention may be coupled to other mechanical or electrical devices. In this sense, the diaphragm acts as a transducer or prime mover.

The above-mentioned objects and advantages of the present invention will be more clearly understood when considered in conjuntion with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE FIGURES FIG. I is a perspective view of the present invention.

FIG. 2 is a sectional view taken along a plane passing through section line 2-2 in FIG. 1.

FIG. 3 is a sectional view of the structure of the present invention when utilized as a missile fuze.

DETAILED DESCRIPTION OF THE INVENTION Referring to the figures, and more particularly FIG. 1 thereof, the exterior appearance of the present sting oscillator is illustrated. A generally frusto-conical housing 10 is provided. The housing has a first frustoconical section 12 that integrally extends to a second annular-cylindrical section 14. An axially disposed annular cavity 16 extends through the axial length of the cylindrical section 14. A sting or rod 18 projects outwardly from the outward end of the cavity 16 for triggering pressure oscillations.

FIG. 2 illustrates the interior components of the present invention in greater detail. A first means of mounting the sting 18 comprises a plurality of spaced ribs 20 that extend between the sting and a confronting surface of the housing. To the right or rearwardly of the sting 18 is the enlarged portion of the resonant cavity 16. An annular inlet or passageway 22 permits a fluid flow along the length of the sting 18 to the cavity 16. With the components of the present invention as shown and described, the sting I8 and cavity 16 are disposed axially or centrally in either a steady free flow field of fluid or in the path of ajet flow, as derived from a nozzle 30 that is positioned in an optional housing extension 28. Vortices shed from the sting 18 causes the cavity to trigger into oscillation. In actuality, the pressure within the cavity 16 alternately builds up and decreases with periodic regularity. pressure waves are exhausted out from the cavity'and inlet 22 to be disbursed at the frequency of oscillation.

A diaphragm 24 defines the rearward end or closure of the cavity 16. As the pressure pulsations or variations occur, the diaphragm undergoes oscillations. In

the embodiment illustrated in FIG. 2, the diaphragm is edge-clamped as shown at 26. A rod 27 is connected to the center of the diaphragm 26, at one end thereof. The opposite end is connected to a suitable utilization means, which does not form a part of the present invention per se. The utilization means may include a mechanical mechanism or an electromagnetic device for generating oscillating AC signals from the mechanical motion of the diaphragm 24. The actual transducers or mechanical mechanisms that may be connected to the present invention are well known. For example, in the case of an electro-magnetic transducer, an electrical output may be obtained with a utilization means in the form of a ringtone/Helmholtz oscillator or an edgetone oscillator.

Another point to bear in mind is the diaphragm need not be edged clamped, as shown in FIG. 2. Instead, the diaphrgm may be secured at its center while the edge is free to oscillate. The advantage to such a design is an amplification effect of oscillations, due to the greater displacements at the edge of the diaphragm than towards the center.

FIG. 3 specifically illustrates the utilization of the present invention as a missile fuze.

As illustrated in the figure, a nose cone 32 is provided as a surrounding housing for the interiorly disposed sting oscillator. Reference numeral 34 denotes the interior housing portion for the device. A number of spaced ribs 36 support an axially disposed and rearwardly extending sleeve or casing 38 which has the primary function of journaling a spring biased sting 56. The inward end of the casing 38 is secured to the center of diaphragm 40. As will be noticed, the edges of the diaphragm 42 are freely suspended to permit their oscillation. As previously mentioned, this type of mounting has the advantage of an amplified oscillating displacement. An actuator rod 43 may be employed to connect the outwardly oscillating portion of the diaphragm 42 to a utilization means, as previously discussed. of course, it is to be understood that the particular clamping arrangement of the diaphragm and the disposition of the utilization means, relative to the diaphragm, may be altered.

In the embodiment shown in FlG. 3, a rod 44 is journaled in the casing 38. Two spaced lock rings 46 are permanently mounted along the mid-point of the rod 44. A holding pin 48 extends through the casing 38 and is disposed between the lock rings 46 to hold the sting 56 in a retracted position. A spring 50 bears against the inward end of the casing 38, at one end of the spring. The opposite end bears against one of the lock rings 46 to cause outward biasing of the sting 56. However, the holding pin 48 prevents the extension of the sting.

A sealing cover or diaphragm 58 is provided to keep debris from entering the device and possibly becoming lodged in cavity 54. As a design criterion, it would be desirable to make the cover difficult to remove by hand, thus averting mistaken arming. However, the diaphragm should be easily ruptured when a missile, to which the fuze is connected, is fired from a gun.

During firing, the setback forces cause sting 56 to move slightly backwards relative to the remainder of the structure against the biasing of spring 50, thereby breaking or otherwise rleasing holding pin 48 which in turn releases spring 50 so as to move sting 56 into its extended position, indicated in phantom at 52.

There are several interesting features about this design when utilized as a fluidic fuze for a missile. The housing portion 34 would be used as an antenna for the output electrical signal from a utilization means that takes the form of an electrical oscillator. Assuming, that the illustrated utilization means is an electrical generator, the present fuze design presents a safe approach. This is because the sting takes a few milliseconds to arm, and the generator requires some charging time. Thus, the round is safe until it is some distance from the gun. Arming the fuze occurs when the sting tears through the diaphragm 58. With the sting in an extended position, the cavity 54 is actuated into resonance during flight. Since drag on the sting would normally be able to force it back into the nose cone during supersonic flight, a detent or other suitable mechanism could be provided to lock the rod, and its connected sting 56, in a protracted or extended position.

With the invention thus described, the numerous advantages of the present invention as a sting oscillator will be appreciated. Again, it is to stressed that applications for the disclosed sting oscillator are varied. in addition, although the present invention has been described in terms of a three dimensional version, a two dimensional version is likewise intended and its construction would be obvious to one of ordinary skill in the art based on the present invention.

it should be understood that the invention is not limited to the exact details of construction shown and described herein for obvious modifications will occur to persons skilled in the art.

What is claimed is:

1. A fluidic oscillator comprising:

a housing having a passageway through which fluid passes;

a resonant cavity formed in the housing and in communication with the passageway;

a diaphragm mounted in the cavity for responding to oscillating fluid pressure waves in the cavity;

a rod axially positioned in said passageway, said rod being wholly retracted within said passageway when said fluidic oscillator is inactive;

and means for extending one end of said rod outwardly beyond said housing, for triggering oscillating fluid pressure waves in said cavity, when said fluidic oscillator is active.

2. The subject matter of claim 1 wherein the outward end of said rod terminates in a single point.

3. The subject matter of claim 1 wherein said lastnamed means include spring means.

4. The subject matter of claim 1 wherein said lastnamed means are mounted on said diaphragm.

5. The structure set forth in claim 1, further including a frangible seal over the outward end of said passageway when said rod is wholly retracted and said fluidic oscillator is inactive, said frangible seal being pierceable by said rod when said rod is extended and said fluidic oscillator is active.

6. The subject matter of claim 5 wherein the outward end of said rod terminates in an enlarged projection.

7. The subject matter as described in claim 1 wherein rib means are mounted between the rod and a confronting surface of the passageway for supporting the rod axially in the passageway.

8. The structure recited in claim 1 together with actuator means connected between the diaphragm and a rects a fluid jet of relatively narrow radius, into the passageway'.

12. The subject matter set forth in claim 1 wherein the diaphragm is mounted in the cavity as an inward wall thereof, with the diaphragm center coaxial with the axis of the cavity which is likewise coaxial with the axis of the passageway and the rod. 

1. A fluidic oscillator comprising: a housing having a passageway through which fluid passes; a resonant cavity formed in the housing and in communication with the passageway; a diaphragm mounted in the cavity for responding to oscillating fluid pressure waves in the cavity; a rod axially positioned in said passageway, said rod being wholly retracted within said passageway when said fluidic oscillator is inactive; and means for extending one end of said rod outwardly beyond said housing, for triggering oscillating fluid pressure waves in said cavity, when said fluidic oscillator is active.
 2. The subject matter of claim 1 wherein the outward end of said rod terminates in a single point.
 3. The subject matter of claim 1 wherein said last-named means include spring means.
 4. The subject matter of claim 1 wherein said last-named means are mounted on said diaphragm.
 5. The structure set forth in claim 1, further including a frangible seal over the outward end of said passageway when said rod is wholly retracted and said fluidic oscillator is inactive, said frangible seal being pierceable by said rod when said rod is extended and said fluidic oscillator is active.
 6. The subject matter of claim 5 wherein the outward end of said rod terminates in an enlarged projection.
 7. The subject matter as described in claim 1 wherein rib means are mounted between the rod and a confronting surface of the passageway for supporting the rod axially in the passageway.
 8. The structure recited in claim 1 together with actuator means connected between the diaphragm and a utilization means for transmitting mechanical oscillations from the diaphragm to the utilization means.
 9. The subject matter of claim 8 wherein the actuator means is connected to the center of the diaphragm.
 10. The subject matter of claim 8 wherein the actuator means is connected to an area of the diaphragm, adjacent its outer edge.
 11. The subject matter of claim 1 wherein the inlet of the passageway is in registry with a nozzle which directs a fluid jet of relatively narrow radius, into the passageway.
 12. The subject matter set forth in claim 1 wherein the diaphragm is mounted in the cavity as an inward wall thereof, with the diaphragm center coaxial with the axis of the cavity which is likewise coaxial with the axis of the passageway and the rod. 